First instar

  • Creator
    Topic
  • #58288

    gib
    Participant

    I have looked at a couple of sites devoted to monarchs, but none of the descriptions of the life cycle that I’ve seen covers what I recently observed, so here’s my 2 cents worth.

    I noticed that the young tips of many branches on my swan plant had the leaves pulled together. I found that the small young leaves were held together by silk to make a kind of cocoon – typically the sign of certain garden pests. I opened one up and discovered inside a pale green, almost translucent worm-like creature, which at first I thought was a pest larva but then realised was a first instar monarch caterpillar. There are many on my plant, and ones with signs of recent occupancy, with many small droppings caught in the silk, and the recent occupant can sometimes be detected a short distance away.

    I am surprised that this first chapter in the life of a caterpillar is not more widely documented. Have others seen this?

Viewing 8 replies - 1 through 8 (of 8 total)
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    Replies
  • #58402

    Jacqui
    Moderator
    #58400

    Raymond
    Participant

    New born and first instar Monarch caterpillars have stripes on them. You may have the Looper caterpillar on your plant.

    #58302

    gib
    Participant

    Thanks for clearing that up, Jacqui. Good to know it’s benign. I wonder if, like the monarch, it is protected by the swan plant chemicals.

    #58296

    Jacqui
    Moderator

    Sounds like the swan plant flower moth, Glyphodes onychinalis, which is well documented in other parts of the forum. Try searching on its name for pictures etc – very pretty moth – and only eats the flowers so not a threat to the monarchs.

    #58295

    gib
    Participant

    I opened another “cocoon” and found a pale green grub about 10mm long. Obviously not a monarch, no idea what it is. I’d like to know, in case it’s a predator.

    #58294

    gib
    Participant

    This is where I read about the appearance of the 1st instar:
    https://monarchjointventure.org/monarch-biology/life-cycle/larva/guide-to-monarch-instars
    It seems that the stripes develop later in this stage. But now I’m becoming convinced that I was wrong, because the worm/grub that I saw was much too big to be the 1st instar, and nowhere do I see mention of the silk cocoon made of leaves. Also I can now see several tiny caterpillars, about 4 – 6 mm, which are obviously 1st instars. So now I’m very puzzled – what is making the cocoons?

    #58293

    gib
    Participant

    Hmmm, that’s got me thinking, Leslie. As I said, my first impression was that it was another critter, then after reading what the first instar looked like, I changed my mind. I haven’t seen any other insects on the plant (except for the shield bug, and a mantis that I removed yesterday.) I’ll try to find the site where I read that the first instar was pale green/translucent.

    #58292

    LeslieD
    Participant

    I’ve only ever seen the usual stripy caterpillars as first instars, and mine have come straight out of the egg with their stripes on. And they don’t form webs, they just hang out, usually at the tips where the leaves are tender. Maybe you have some other critter on your plants?

Viewing 8 replies - 1 through 8 (of 8 total)

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